Device for grounding feed cables between transmitters or receivers and antennas

ABSTRACT

The present invention relates to a device for grounding feed or supply cables between transmitters or receivers and antennas or aerials, whereby at least one connector, through an aperture in the outer sheath of the supply cable, is in contact with an exposed portion of an inner conductor of the supply cable for grounding the inner conductor through at least one ground wire cooperating with the connector. In order to obtain the grounding of the inner conductor with few members, to mount the grounding device quick and safe and to reinforce the supply cable at the spot weakened by the aperture, the connector is provided on a bracket which in cooperation with at least one other bracket engages the supply cable and is located thereon so that the connector is directed into the aperture and is in contact with the exposed portion of the inner conductor, whereby the bracket with the connector has sealing members which engage the outer sheath around the aperture therein when the bracket with the connector is located on the supply cable.

The present invention relates to a device for grounding feed or supplycables between transmitters or receivers and antennas or aerials,preferably between radio or television transmitters or radio ortelevision receivers and radio or television aerials, whereby at leastone aperture is provided in an outer sheath of the supply cable forexposing an inner conductor in said supply cable and whereby at leastone connector is in contact with the exposed portion of the innerconductor for grounding said inner conductor through at least one groundwire cooperating with the connector.

Supply cables are grounded to prevent lightning strokes in the aerialfrom causing damages in the transmitter or receiver. If e.g. the aerialis mounted on a high mast, the supply cable is grounded in the mast atabout every fiftieth meter and also in the ground at the base of themast.

The devices for grounding the supply cable however, have some drawbacks.This result in that it takes an annoyingly long time to mount thedevices, it is difficult to obtain a satisfactory sealing at thegrounding point and the supply cable is weakened through the aperturestherein.

The object of the present invention has primarily been to eliminate saiddrawbacks by means of a simple device. This is arrived at according tothe invention by providing the abovementioned device substantially withthe characterizing features of subsequent claim 1.

Since the device is provided with said characterizing features,grounding can occur by means of a few members, the mounting or assemblytime is substantially reduced, a very good sealing is obtained aroundthe aperture in the outer sheath and the weakened spot at said aperturein the outer sheath can be reinforced.

The invention will be further described below with reference to theaccompanying drawings, wherein

FIG. 1 schematically illustrates an aerial mast with a supply cablebetween the aerial and a transmitter or receiver, which supply cable isgrounded at some locations with devices according to the invention;

FIG. 2 with a side view illustrates a portion of the supply cable ofFIG. 1 provided with a device according to the invention of which onehalf is shown with a side view and the other half with a longitudinalsection;

FIG. 3 is a view III--III of the device of FIG. 2;

FIG. 4 is a section IV--IV through the device of FIG. 2;

FIG. 5 is a section V--V through the supply cable of FIG. 3 and an endview of the device of FIG. 3;

FIG. 6 is an enlarged section VI--VI through the device of FIG. 3;

FIG. 7 with a plan view illustrates the inner side of a bracket formingpart of the device of FIG. 1; and

FIG. 8 is a section VIII--VIII through the bracket of FIG. 7.

In FIG. 1 a mast 1 having an aerial 2 and a feed or supply cable 3mounted between said aerial 2 and a transmitter or receiver 4, isschematically illustrated. The aerial 2 can be a radio or televisionaerial and the transmitter or receiver 4 a radio or televisiontransmitter or a radio or television receiver. In order to preventdamages on the transmitter or receiver 4 if the lightning strikes theaerial 2, the supply cable 3 is grounded at several locations, namelythrough grounding devices 5 which are schematically shown in FIG. 1. Anumber of such grounding devices ground or earth the supply cable 3against the mast 1 and a grounding device 5 grounds the supply cable 3preferably against the ground 6 at the base of the mast 1.

In order to locate the grounding devices 5 at certain parts 7 of thesupply cable 3, two apertures 8, 9 are provided at each such part 7 inopposite portions of the outer sheath 10 of said supply cable 3. Theapertures 8, 9 are made so that an inner conductor 11 provided in thesupply cable 3 is partly exposed (portion 12). The inner conductor 11has in the illustrated embodiment a circular cross-sectional form, it iscorrugated in longitudinal section and it consists of conductivemetallic material, preferably copper material.

The apertures 8, 9 can be made by a suitable appliance, e.g. by means ofa punch pliers (not shown), which preferably can bring along the cutaway pieces of the outer sheath 10 when the punch pliers is opened.

A connector 14 or 15 is connected with the respective exposed portion12, 13 of the inner conductor 11, and cooperates with a ground wire 16.This ground wire 16 is joined to earth, which means that the innerconductor 11 is grounded or earthed at two opposite spots at eachexposed portion 12.

Each connector 14, 15 is provided on a bracket 17 or 18, and thesebrackets 17, 18 are connected with each other by means of fourtightening screws 19-22 or similar tightening or clamping means. Thesetightening screws permit release of one of the brackets from the other,whereafter said brackets 17, 18 can be placed opposite to each other onthe part 7 of the supply cable 3 provided with the apertures 8, 9.Thereafter, the tightening screws 19-22 can once again be screwed intothe released bracket and by tightening said tightening screws 19-22,said brackets 17, 18 can be brought to engage the supply cable 3 withpressure, whereby each connector 14, 15 is directed into the respectiveaperture 8, 9 and in contact with the respective exposed portion 12, 13of the inner conductor 11.

Each bracket 17, 18 includes sealing members 23 and 24 respectively,which engage the outer sheath 10 around the respective aperture 8, 9 toprevent moisture and dirt and/or anything else from penetrating throughsaid aperture 8, 9 and into the exposed portions 12, 13 of the innerconductor 11.

The length L of the brackets 17, 18 is selected so that they span overthe apertures 8, 9 and engage the part 7 of the supply cable 3 onopposite sides of said apertures 8, 9 in such a way and/or with such apressure that they reinforce and/or stiffen the supply cable 3 foropposing the weakening of said supply cable 3 caused by the provision ofthe apertures 8, 9.

At the embodiment illustrated in the drawings, each bracket 17, 18 isformed as a half tube member 25 and 26 respectively, which e.g. can havethe shape of a half hollow cylinder or substantially a half hollowcylinder. Each half tube member 25, 26 has, in cross section, the shapeof its inner side 27, 28 adapted or substantially adapted to thecross-sectional shape of the outer side 29 of the outer sheath 10 of thesupply cable 3. In the embodiment shown, the tube members 25, 26 have,in cross section, semicircularly shaped inner sides 27 and 28respectively, and the outer side 29 of the outer sheath 10 is, in crosssection, circular or substantially circular.

Each sealing member 23, 24 consists of, in the embodiment shown, asealing ring 30 or 31 of elastic material, preferably rubber material,which extends around the respective connector 14, 15. Each sealing ring30, 31 is preferably placed in a groove 32 or 33, so that a portionthereof extends out of the groove 32. The sealing ring 30, 31 can beglued in the groove 32, 33 or retained therein in any other way.

Each groove 32, 33 is located so that two portions 34 or 35 ofrespective sealing ring 30, 31, extending at least partially intransverse direction relative to the respective half tube member 25, 26,are provided on opposite sides of the respective connector 14, 15,substantially between the connector 14, 15 and the end sides 36, 37 ofsaid half tube member 25, 26. Furthermore, two longitudinal portions 38or 39 of the respective sealing ring 30, 31 extending in thelongitudinal direction of the respective half tube member 25, 26 arelocated on opposite sides of the respective connector 14, 15 andsubstantially between said connector 14, 15 and longitudinal edges 40,41 of the inner side 27, 28 of the respective half tube member 25, 26.The longitudinal portions 38, 39 are linear or substantially linear andrun in parallel with each other or substantially in parallel with eachother, while the partially transverse portions 34, 35 are arcuate andconnect the linear portions 38, 39 with each other.

Each connector 14, 15 is preferably elongated and extends in thelongitudinal direction of the half tube member 25, 26 as well as of theinner conductor 11, and is preferably centrally or substantiallycentrally located in the respective half tube member 25, 26.

Each connector 14, 15 has a length and width which is only slightly lessthan the length and width of the aperture 8, 9 and is mounted on theinner side 27, 28 of the respective half tube member 25, 26 so that itprotrudes into said respective aperture 8, 9. Each connector 14, 15 alsohas such a height that it with an end surface 42 and 43 respectively,engages the inner conductor 11. Since the inner conductor 11 in theillustrated embodiment is corrugated in the longitudinal directionthereof, the end surface 42, 43 of the respective connector 14, 15 isalso corrugated in its longitudinal direction. Furthermore, the endsurface 42, 43 preferably has the same arcuate shape in its transversedirection as the inner conductor 11.

Each connector 14, 15 preferably has a length which substantiallycorresponds with or is slightly less than half the length of therespective half tube member 25, 26 and preferably a width whichsubstantially corresponds with 25% of the diameter of the inner side 27,28 of the respective half tube member 25, 26.

Each connector 14, 15 and respective half tube member 25, 26 arepreferably manufactured as a unit of the same conductive metallicmaterial, whereby said unit preferably consists of brass with asilver-plated surface.

The tightening screws 19-22 are provided so that the half tube members25, 26 can be easily disassembled or opened so that they quickly can bemounted on the supply cable 3 simply by positioning them on oppositesides thereof. Thereafter, the half tube members 25, 26 can be clampedaround the supply cable 3 until their sealing rings 30, 31 with pressureengage the outer side of the outer sheath 10, while their connectors 14,15 are in contact with the inner conductor 11.

Each tightening screw 19-22 preferably has an untapped inner portion 44closest to the screw head 45 and an outer threaded portion 46 (see FIG.6). The inner untapped portion 44 extends with play through the hole 47therefor in e.g. one of the half tube members 25 and the threaded outerportion 46 is screwed into threads in the hole 48 therefor in the otherhalf tube member 26.

The hole 47 in one of the half tube members 25 preferably has threads 49along at least a part of its length (e.g. at the entrance of the hole47), so that the tightening screw 19-22 does not loosen and fall downout of the tube member 25 when said screw is screwed out of the hole 48in the other tube member 26.

Both the half tube members 25, 26 together encircle the part 7 of thesupply cable 3 including the apertures 8, 9 and they can be clampedtogether by means of the tightening screws 19-22 so that they engageeach other through opposing surfaces 50, 51. Hereby, contact is obtainedbetween the half tube members 25, 26 so that their respective connector14, 15 can be grounded with only one ground wire 16 which e.g. isconnected with the half tube member 25. The ground wire 16 can bemounted on said half tube member 25 by means of a mounting or fixingscrew 52 or another means of attachment.

Every half tube member 25, 26 can be shaped to surround half orsubstantially half the supply cable 3, the size and outer shape of boththe half tube members 25, 26 are similar or substantially similar andthe connectors 14, 15 have the same or substantially the same form andthe same or substantially the same position on both the half tubemembers 25, 26.

The invention is not limited to what is described above and illustratedin the drawings, but may vary within the scope of the following claims.Thus, the invention can be used at feed or supply cables for othertransmitters/receivers than television transmitters/receivers and radiotransmitters/receivers. It is possible to use more than two brackets 17,18 to hold one or more connectors 14, 15 in contact with the innerconductor 11; only one of several brackets 17, 18 may have a connector14 or 15; there may be more than one connector 14, 15 on a bracket 17 or18; the brackets 17, 18 may have other shapes than half tube membersand/or hollow cylinders; the brackets 17, 18 do not need to have similarforms--one bracket may e.g. be shaped as a half tube and the other inanother way; the brackets may entirely or partly be of conductivematerial; there may be another number than four tightening screws 19-22;there may be other clamping means than tightening screws 19-22; thesealing members 23, 24 may be of another type than sealing rings 30, 31;the sealing members may be located in other ways than shown; there maybe more than one sealing member on every bracket 17 and 18 respectively;the tightening screws 19-22 may be of another type or other types oftightening or clamping means may be used.

I claim:
 1. Device for grounding feed or supply cables betweentransmitters or receivers and antennas or aerials, preferably betweenradio or television transmitters or radio or television receivers andradio or television aerials, whereby at least one aperture is providedin an outer sheath of the supply cable for exposing an inner conductorin said supply cable and whereby at least one connector is in contactwith the exposed portion of the inner conductor for grounding said innerconductor through at least one ground wire cooperating with theconnector, characterized in that the connector is provided on a bracketwhich in cooperation with at least one other bracket engages the supplycable and is located thereon so that the connector is directed into theaperture and is in contact with the exposed portion of the innerconductor and that the bracket with the connector has sealing memberswhich engage the outer sheath around the aperture therein when saidbracket with the connector is located on the supply cable.
 2. Deviceaccording to claim 1, characterized in that a length (L) of the bracketsis selected so that said brackets span over the aperture and engage theouter sheath on opposite sides of said aperture in such a way and/orwith such a pressure that they reinforce and/or stiffen the supply cablefor opposing the weakening of said supply cable caused by the provisionof the aperture.
 3. Device according to claim 1, characterized in thatthe connector is elongated and extends in the longitudinal direction ofthe bracket as well as of the inner conductor.
 4. Device according toclaim 1, characterized in that the connector is located centered orsubstantially centered in relation to opposing end sides of the bracket,that the connector, in cross-sectional direction through the bracket, iscentrally or substantially centrally located on an inner side of thebracket, which inner side, in said cross-sectional direction, is arcuatecorresponding to or substantially corresponding to an outercross-sectional shape of the supply cable, that the connector preferablyhas a length which corresponds to or is slightly less than half thelength of the bracket and that the connector preferably has a widthwhich corresponds to substantially 25% of a diameter of the arcuateinner side of the bracket.
 5. Device according to claim 1, characterizedin that the bracket and the connector consist of the same conductivemetallic material and are manufactured in one piece, whereby saidbracket and said connector preferably consist of brass with or without asilver-plated surface.
 6. Device according to claim 1, characterized inthat the bracket in its cross-sectional direction has an inner side, theshape of which is adapted to or substantially adapted to the outer sideof the outer sheath of the supply cable in cross section, whereby thebracket in said cross-sectional direction has a semi-circular orsubstantially semicircular inner side, which is adapted to an incross-sectional direction circular or substantially circular outer sideof the outer sheath.
 7. Device according to claim 1, characterized inthat the sealing members comprise or consist of at least one sealingring of elastic material, which sealing ring preferably is located in agroove in the inner side of the bracket, which groove runs around theconnector.
 8. Device according to claim 1, characterized in that bothbrackets have connectors which are in contact with different exposedportions of the inner conductor and that both connectors cooperate withone and the same ground wire for grounding both the exposed portions ofthe inner conductor.
 9. Device according to claim 1, characterized inthat the connector is located on an inner side of the bracket, that theconnector has only a slightly smaller length and width than the aperturein the outer sheath and that the connector has such a height that itwith an end surface engages the inner conductor.
 10. Device according toclaim 9, characterized in that the shape of the end surface of theconnector is adapted to the shape of the inner conductor, whereby saidend surface of said connector preferably has the same or substantiallythe same corrugation or wave form in its longitudinal direction as theinner conductor has in its transverse direction.
 11. Device according toclaim 1, characterized in that the sealing members of the bracket extendaround the connector.
 12. Device according to claim 11, characterized inthat portions of the sealing members, extending at least partially intransverse direction relative to the longitudinal direction of thebracket, are provided substantially between the connector and end sidesof said bracket, and that longitudinal portions of the sealing members,extending in the longitudinal direction of the bracket, are locatedsubstantially between the connector and longitudinal edges of the innerside of said bracket.
 13. Device according to claim 11, characterized inthat the longitudinal portions of the sealing members are linear orsubstantially linear and run in parallel or substantially in parallelwith each other, and that the at least partially transverse portions ofthe sealing members are arcuate and connect the linear portions witheach other.
 14. Device according to claim 1, characterized in that thebrackets are connected with each other by means of tightening screws,which permit disassembly or opening thereof for mounting on the supplycable, and that the tightening screws, by screwing in said screws, cantighten the brackets so that their sealing members with pressure engagethe outer sheath of the supply cable.
 15. Device according to claim 14,characterized in that each tightening screw has an uptapped innerportion closest to a screw head forming part of the tightening screw andan outer threaded portion, that the untapped inner portion is adapted toextend with play through a hole therefor in one of the brackets and thatthe threaded outer portion is adapted to be screwed into a threaded holein the other bracket.
 16. Device according to claim 15, characterized inthat the hole in said one bracket, through which the untapped innerportion of the tightening screw is adapted to extend, has threads alongat least a part of its length in order to prevent the tightening screwfrom loosening from said bracket when the threaded outer portion thereofis screwed out of the threaded hole in said other bracket when e.g. saidbrackets are disassembled or released from each other.
 17. Deviceaccording to claim 1, characterized in that at least one of the bracketsis formed as a half tube member or substantially as a half tube member.18. Device according to claim 17, characterized in that both bracketsare formed as half tube members or substantially as half tube membersand that both said half tube members together encircles the part of thesupply cable provided with the aperture.
 19. Device according to claim18, characterized in that each half tube member has a connector whichthrough each one aperture in the outer sheath is in contact withopposite sides of the inner conductor, and that both the half tubemembers includes sealing members which engage the outer sheath of thesupply cable around both apertures therein.
 20. Device according toclaim 18, characterized in that opposing surfaces of the half tubemembers engage each other to obtain contact therebetween, and that oneof said half tube members includes a ground wire for grounding both halftube members contacting each other.
 21. Device according to claim 18,characterized in that each of the half tube members surrounds half orsubstantially half the supply cable, that the size and outer shape ofboth half tube members are the same or substantially the same, that theconnectors have the same or substantially the same shape and the same orsubstantially the same location on both said half tube members and thatboth said half tube members consist of conductive metallic material,preferably brass with silver-plated surface.
 22. Device according toclaim 18, characterized in that both the half tube members are shaped ashalf hollow cylinders or substantially as half hollow cylinders.